Melt-textured YBa/sub 2/Cu/sub 3/O/sub 7/ for low-field applications in microwave devices

We report the results of an investigation of microwave power loss at 10 GHz in YBCO at 77 K. The samples are melt-textured YBa/sub 2/Cu/sub 3/O/sub 7/ (123) with 28 mole % Y/sub 2/BaCuO/sub 5/ (211) inclusions and x% of Ag added to bridge the gaps at the grain boundaries. The sample with 10% Ag shows critical currents >10/sup 8/ amp/m/sup 2/ at 77 K. Measurements down to 77 K show that microwave power loss drops more sharply (through T/sub c/ of 89 K) with higher Ag content. DC magnetic-field-induced microwave absorption (MWMA) recorded at 77 K shows that in these samples the low (/spl sim/10 mT) field loss is drastically reduced with respect to that in typical YBCO ceramics.<
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